Most women misdiagnose their real hair type...and end up with shampoos, conditioners, and styling products that are all wrong for them

Run into me midday and you'd never know I started the morning with gobs of anti-frizz cream and a half-hour flatiron session. By that point, my thick hair has morphed into a poufy mess. A hairstylist finally uncovered why my frizz-fighting product was failing me: water. As the first ingredient listed on the cream's label, H2O made the product a great option for fine, damaged hair—but not potent enough to manage my rebellious tresses. "Women research the ingredients in their skin-care products, but few do with their hair products," says cosmetic chemist Perry Romanowski, author of The Beauty Aisle Insider.

Complicating matters further, many of us don't really know what type of hair we have. It's not just oily or dry. Hair is categorized by three characteristics: porosity (how much moisture it can hold), elasticity (how easily it breaks), and texture (how thick it is). This equation takes into account the hair you were born with, plus what you've done to it (color, blow-dry, style). "Once you figure out where your hair falls within these categories, you'll be able to choose products with ingredients that will make it look its best," explains Elizabeth Cunnane Phillips, a trichologist (hair and scalp pro) at the Philip Kingsley Institute in New York City. Step one in ending bad hair days? Follow the arrows to determine your true hair type, then discover ingredients, products, and styling tricks tailored for it.

What your hair has in healthiness, it lacks in volume. Each strand is thin and can't hold its own against certain hair-care ingredients. Focus on tress-plumping products and avoid heavy ones, which will make hair fall flat within hours of styling.

Shampoo
Do it every day. "Sebum, dirt, and sweat buildup can make hair lifeless and increase shedding and thinning," explains Phillips.

Look for words like thickening, volumizing, or amplifying and ingredients like natural cellulose and polymers (both add bulk by filling in the spaces between strands). "Go for a shampoo that's translucent—opaque formulas generally have more intense moisturizing ingredients, which may interfere with volume," says Jeni Thomas, a senior scientist at Procter & Gamble. Try Bumble & Bumble Thickening Shampoo (1), $23, bumbleandbumble.com.

While achieving fullness is a challenge for all skinny strands, the "damaged" part of your equation creates a double whammy: You need to find repairing products that don't make hair go limp. Balance volume and moisture and you'll restore your hair's luster.

Shampoo
Choose a sudser that's based on your scalp. It's oily if your roots get greasy within a day of washing; it's dry if it feels tight or irritated with occasional flakes.

Post-shower, tame and soften with a spray-on conditioner that has cyclopentasiloxane. Try Garnier Fructis Triple Nutrition Nutrient Spray for Damaged Hair, A $6, at drugstores. Mist it over the damaged area.

Deep-condition once a week with a mask laced with kernel oil or wheat-germ oil. Try Moroccanoil Weightless Hydrating Mask, $39, moroccanoil.com for salons. Before shampooing, apply to the bottom half of dry hair for 15 minutes.

Just call you Goldilocks—not too much hair, not too little, but just right (and in fab condition). That means no ingredients are off limits, and any haircut or style you want is attainable. The goal is to keep your locks as pristine as they are now.

Shampoo
Wash every other day with a formula geared for your scalp. If your roots get greasy fast, you're oily; fruit acids will nix grease and product buildup. If your scalp feels tight or irritated and you have occasional flaking, you're dry; hydrating babassu, olive, or sesame-seed oil will help. In either case, you also want wheat or oat protein to retain hair's resiliency. For an oily scalp, try Redken Hair Cleansing Cream (1), $14.50, redken.com for salons. For a dry scalp, try Fekkai Brilliant Glossing Shampoo,$25, ulta.com.

If you have waves or curls, look for a blend of smoothing keratin protein and behentrimonium chloride, a waxier conditioner that helps tame tangles. Try Suave Professional Keratin Infusion Smoothing Conditioner, $3.49, at drugstores.

Your strands are thick enough that any hairstyle works, but not so thick that they're tough to manage. The problem? Overstyling (or coloring) has caused split ends, frizz, and dullness. Strengthen with protein and you'll prevent breakage.

To play up waves, work an alcohol-free gel into damp hair, one small section at a time, gently twisting each as you go. Try L'Oreal Paris Ever Style Curl Defining Gel, $7, at drugstores. Air-dry or use a diffuser.

To straighten, work a cream through damp hair. Try John Frieda Frizz-Ease Straight Fixation Smoothing Creme, $6, at drugstores. If you blow-dry, Shorter says to use a boar-bristle brush.

There's an irony to fat strands: Their wide diameter makes them voluminous and sexy but also potentially coarser, frizzier, and less shiny than their thinner counterparts. Your mission: Condition! Hydrated thick hair is easier to style and less poufy.

Shampoo
Try to wash only once every three days—retaining your hair's natural oils makes it lie better.

A cocoa butter-derived cleanser will lock in moisture, making hair softer and gleamier. Or pick one that contains shea butter or meadowfoam oil, both of which are rich in fuzz-taming fatty acids. Try Fresh Meadowfoam Cream Treatment, $32, fresh.com.

Stylers
Avoid products with water as the first ingredient (see intro, page 150), but don't necessarily skip those that contain alcohol—as long as it's cetyl alcohol, cetearyl alcohol, or stearyl alcohol. These are all fatty acids, which are excellent emollients.

Make sure the serum is distributed evenly so there aren't spots of blahness or greasiness. Shorter recommends separating wet hair into four sections (two on top, two on bottom). Start with a quarter-size amount for the whole head, and divide that into four. Rake through each section from roots to tips.

If straightening hair with a dryer, use a boar-bristle brush to tame strands delicately.

Your hair is hard to control as is. Throw in lots of blow-drying, flat-ironing, dyeing, or straightening, and no wonder it's disobeying like a petulant child. Coddle it with mega moisturizers and mega frizz fighters. And try to use heat tools sparingly.